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Re: restoring FC1 to *new* partition from tar archive



It would appear that on May 10, Luciano Miguel Ferreira Rocha did say:

> There's also:
> `--numeric-owner'
>      The `--numeric-owner' option allows (ANSI) archives to be written (1)
>      without user/group name information or such information to be
>      ignored when extracting.  It effectively disables the generation
>      and/or use of user/group name information.  This option forces
>      extraction (2) using the numeric ids from the archive, ignoring the
>      names.
> 
> Two things:
> 1) If used when creating archives, the user/group information stored in
> the archive for files will be only numeric
> 2) If used when extracting, it will use only the numeric information and
> disregard the names.
<snip>
> > Which option isn't even mentioned in man tar. Now here is the part I
> > don't understand. If it's supposed to be more reliable when extracting
> > to a different system, How would it deal with file belonging to
> > user=goodDube has UID=1001 on the source file system when on the
> > destination file system UID=1001 is held by user=EvilTwin???
> 
> If the option --numeric-owner is used:
> - the file ownership is changed to uid 1001, that belongs to EvilTwin
> 
> Without the option (and with the information that 1001=goodDube in the
> archive):
> 1) if a goodDube user also exists in the destination system, lets say with
> uid=1010:
>   - the file ownership is changed to goodDube's, 1010. That's what you
>     usually want
> 2) if such user doesn't exist:
>   - the file ownership is changed to uid 1001 (the only usable information),
>     that belongs to EvilTwin
> 
> Why you don't want 1 in your case:
> You're creating a full backup. When you restore it, you're going to use it
> as is, with the *stored* passwd and group files. *Not* the ones being used
> in the system while you extracted the files.

Thanks again Luciano, I much appreciate the informative explanation.

I'm now certain that when/if I ever want to restore any of these tarfiles
I'll want to use the --numeric-owner option.  But since I didn't use
it when I extracted my now in use FC1 with tar on my mdk9.1, I'm
surprised that I didn't have any problems...

I wouldn't expect problems with the user account(s) that I *use* because
root *IS* root, and for the others I carefully insist on replicating the
same exact UIDs on each of my linux. ( I often find a reason as a user to
mount the partition that I was using when I did something to retrieve a
file and didn't want to have to su first, and didn't want to have to
chown my own file back to myself either...) But I'd be very surprised to
learn that for all system accounts (the ones with the nologin shells) all
had the same UIDs on Mandrake as on Fedora. So if any of them actually OWN
any files, then wouldn't MDK tar have looked up the name in MDK's passwd
and assigned UID's accordingly? In which case, I can't figure out why having
system files owned by UID's that match the MDK passwd file didn't break
anything in FC1...

I'm NOT complaining mind you. But If I understood your explanation of
with/without --numeric-owner, then I definitely have to figure it was
pure chance I didn't mess it all up... Unless _YIKES_ maybe I simply
haven't tried to use what ever got broke yet! Now thats a scary thought.

Thanks

-- 
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